Sensitivity

WHAT IT MEANS

Sensitivity is a measure of the signal needed for reasonably noise free reception. We use the IHF -50dB noise value for stereo and mono transmissions. At 50dB hiss is obvious, if not overwhelming. So this is the aerial signal needed for slightly hissy reception. It is much lower than that needed for hiss free reception; the two are very different. Most tuners need around 40µV (forty millionths of a volt, or very little) to provide hissy stereo, and right down to 5µV for hissy mono.

Using a tuner like this under utilises its potential for good sound quality. VHF/FM is a very high quality source when fed a strong aerial signal, with great clarity into the studio with live talk and discussion, and atmospheric live broadcasts. This sense of transparency is lost with a hissy signal.

Leader 3216 Standard Signal Generator.

HOW WE MEASURE IT

We set our Leader 3216 Standard Signal Generator to 4mV output and 100% modulation at 1kHz to set the 0dB reference, in stereo with the pilot on. Modulation is then switched off and the R.F. level reduced until -50dB noise is measured, without IEC A weighting. The R.F. level that produces this condition is then the stereo sensitivity value.

The generator is switched to mono (i.e. pilot off) and level recorded again for a -50dB noise mono sensitivity figure.